The invention relates to a vaporization arrangement for coating substrates disposed in an areal region or passed through an areal region. The arrangement comprises a rectangular vaporization crucible with a crucible rim and a longitudinal axis, as well as a plurality of electron guns, each having an X and Y deflection system. The electron guns are disposed on one side of the crucible axis separately from the crucible in such a manner that their beam axes extend parallel to one another and are directed along planes passing vertically through the crucible axis. It is possible to deflect the electron beams by means of an additional deflecting device onto the surface of the contents of the crucible.
The German Patent No. 2,206,995, discloses an electron-beam vaporizer in which a beam generator works together with one or several vaporization crucibles, the upwardly divided openings of which are constructed circularly. To protect the sensitive cathode, the beam generator lies below the rim of the crucible and the electron beam is deflected by means of a magnetic field through 180 degrees onto the material to be vaporized or into the mouth of the crucible. The deflecting system, required for the generation of the magnetic field, is, however, disposed above a plane which passes through the rim of the crucible, so that a portion of the vapor unavoidably condenses on the deflecting system. It is known that the beam generator may be disposed to one side of and below the crucible rim, so that the electron beam must be deflected through an angle of 270 degrees in order to pass through the mouth of the crucible and strike the material to be vaporized. It is also known that the electron beam of the vaporization arrangements described above may be deflected within of the crucible mouth in such a manner that the material to be vaporized is struck periodically by the migrating electron beam (see German Auslegeschrift No. 2,047,138).
It is a common feature of all of these vaporization arrangements that they represent essentially only a quasi point source of vapor. Even if several of these vapor sources were to be mounted in a row, a highly inhomogeneous vapor stream would still be produced which would lead to a striated distribution of thicknesses when films, foils or other substrates of large surface area are coated.
The German Patent No. 2,812,285 discloses two electron guns, each with with an X-Y deflection system, with which practically the whole of the surface of the material to be vaporized may be acted upon by a defined energy distribution per surface element, and which may be assigned to a rectangular vaporization crucible with a longitudinal crucible axis. By these means, it is possible to metallize a plurality of substrates, disposed over a larger surface region, largely homogeneously with layers of alloys. For this known solution, however, the electron guns are disposed above the vaporization crucible, so that special shielding devices must be provided to ensure that the parts of the electron guns, which protrude into the vacuum chamber, are not exposed to an impermissible extent to the condensation of vapor. This known arrangement, however, is limited to the use of two electron guns. Because the possibility of deflecting the two electron beams is likewise limited, the maximum length of the crucible is therefore also limited. Moreover, vaporizing crucibles are not assigned their own magnetic field, so that a large portion of the electrons is reflected from the surface of the fused material to be vaporized; i.e., from the bath surface. As is furthermore evident from the German Patent No. 2,812,311, the reflected electrons can be utilized in an advantageous manner for additionally heating the substrates, should this be beneficial for the coating process described. However, since the substrates may not be heated to arbitrarily high temperatures, the output of the electron guns is also necessarily limited, so that the throughput of substrates through such equipment is likewise limited. Such an arrangement is totally out of the question for heat-sensitive substrates.
The state of the art also includes a vaporizing arrangement of the initially described type, in which several electron beam guns with parallel beam axes (defined by their beam control tubes) are disposed on each side of a rectangular vaporization crucible and in which the beam axes lie in mutually parallel, vertical planes, which in turn are perpendicular to a further plane that passes perpendicularly through the longitudinal crucible axis. The deflecting systems assigned to each individual electron gun here are, however, above a plane passing through the rim of the crucible, so that the deflecting systems and the outlets of the electron guns encounter vapor, reflected electrons and heat radiation. With such an arrangement also, the total electric power that can be supplied is limited, particularly since the problem also exists here that the unavoidably reflected electrons strike the substrates and components of the installation, thus heating them additionally. Likewise, no provisions have been made in this known arrangement to assign a magnetic deflecting field directly to the vaporization crucible.
It would be conceivable to provide pole plates at the narrow sides of the vaporization crucible in order to provide an additional magnetic deflecting field in the region of the vaporization crucible, by means of which the electron beams can be deflected onto the material to be vaporized. Such a possibility, however, is made difficult by the largely arch-shaped or barrel-shaped path of the lines of flux, which would lead to considerable inhomogeneities in the beam deflection. Such a vaporization arrangement therefore would have to be divided into several individual crucibles, and pole plates would have to be introduced in the spaces between the individual crucibles, in order to be able to bring about a reliable deflection of the beam. Such an arrangement is described in the German Auslegeschrift No. 2,815,627, however it leads to the disadvantage of a serial arrangement of almost point sources of vaporization.